This invention relates to the production of mouldings from a thermosetting binder (for instance a synthetic resin, such as a polyester or phenolic resin) reinforced by a fibre type filler. The filler is typically a glass fibre sheet, cushion or mat but may alternatively be in the form of textile cloths or even thin metal grids or expanded metal.
In a known method of producing injection mouldings, a filler mat is placed in a mould, the latter is closed, and then the resin is injected under high pressure into the mould. The method has disadvantages; in particular, the method is slow because the operations are all carried out in sequence; in addition, injection under high pressure is likely to move the filler from its proper position.
In another known method of producing reinforced resin components, the component constituents are disposed in a multi-part moulding machine and then kept under pressure during setting of the resin by a press in which the mould is placed. This method is slow, and renders the press necessary for a considerable time. Also, during distribution of the resin throughout the glass fibre mat forming the reinforcement, the pressure exerted by the press can cause a shift or loss of cohesion of said mat.
In an improved pressure moulding method (French patent specification No. EN 70 03120), the press is used only to pressurise the resin in the mould. The mould parts are then locked in a relative position such that the resin remains under pressure while the mould is in the press and then the mould is removed from the press which thus becomes available again. The moulding is left in the mould for the time required for complete setting. One of the causes of the slow cycle in prior art methods is thus removed, but the other disadvantages remain, since all the component constituents must be in place before mould closure starts.